The present invention relates to a capacitor for use in various kinds of electronic apparatus. More specifically, the present invention relates to a capacitor on which a semiconductor element can be directly mounted.
Electrolytic capacitors are typical of capacitors having large capacitance. An electrolytic capacitor comprises a positive electrode element formed of porous valve metal such as aluminum, tantalum, a dielectric layer covering the surface of the electrode element, a solid electrolyte layer formed of functional polymer, manganese dioxide, etc. provided thereon, and a negative electrode layer formed on the outer surface of the solid electrolyte layer. It is entirely molded with a protective material, and terminals are provided at both ends of the molded element.
The above-described conventional solid electrolytic capacitor has a shape of a chip capacitor and is mounted on the surface of a circuit board in the same manner as resistors and other inductance components.
As a result of the increasing popularity of digital circuits, electronic components used in the circuit should have a fast high frequency response. However, the above-described conventional type of solid electrolytic capacitor that is surface mounted on a circuit board, together with semiconductor elements, does not provide the circuit with a satisfactory performance of the high frequency response.
Another problem with conventional electrolytic capacitors is that they employ an oxide layer provided through an electrolytic process for the dielectrics, which layer is weak against a mechanical stress and the capacitors have the polarity. These negative factors are inconvenient in mounting the capacitors on a circuit board.
The present invention addresses the above-described problems and aims to eliminate the drawbacks. A capacitor of the present invention facilitates mounting of a semiconductor element directly on bumps provided on the surface of the capacitor to provide a superior high frequency response.
A capacitor of the present invention comprises a porous metal sheet, an electrode section provided on the porous metal sheet, an organic dielectric layer provided on the porous metal sheet, a solid electrolyte layer provided on the organic dielectric layer, an electrode layer provided on the solid electrolyte layer and an insulating protection layer covering the outer surface of the structure. The insulating protection layer is provided, in at least one surface of the top and the bottom, with through holes reaching the electrode section or the electrode layer. Each of the respective through holes is provided with a conductor electrically connected with either the electrode section or the electrode layer, while it is being insulated from the rest of the layers. Bumps for connection are provided on the conductor protruding above the insulating protection layer, and are to be connected with semiconductor elements or other chip components. Semiconductor elements and various kinds of chip components can be mounted on the bumps provided on the surface of a capacitor of the present invention; which enables a semiconductor device, or a circuit, that is superior in the high frequency response.